在其他人的帮助下，我发现我们最近遇到的高负载与 iotop 中看到的 mysqld 高磁盘写入率有关。现在的平均负载为 3-6，而以前一直保持在 1 左右。我安装了 mytop 来观察所有情况，因为 iotop 中报告了持续的磁盘写入，但实际上根本看不到太多活动：
MySQL on localhost (10.3.7-MariaDB-log) up 0+01:09:53 [11:58:50]
Queries: 959.6k qps: 234 Slow: 125.0 Se/In/Up/De(%): 129/01/02/00
qps now: 100 Slow qps: 0.0 Threads: 3 ( 6/ 2) 113/00/03/00
Cache Hits: 357.2k Hits/s: 87.2 Hits now: 22.4 Ratio: 28.8% Ratio now: 19.7%
Key Efficiency: 100.0% Bps in/out: 127.0k/ 1.9M Now in/out: 73.4k/901.5k
Id User Host/IP DB Time Cmd Query or State
-- ---- ------- -- ---- --- ----------
1 system us 0 Daemon InnoDB purge coordinator
2 system us 0 Daemon InnoDB purge worker
3 system us 0 Daemon InnoDB purge worker
4 system us 0 Daemon InnoDB purge worker
5 system us 0 Daemon InnoDB shutdown handler
5968 root localhost wmnf_www 0 Query show full processlist
6616 wmnfdb localhost wmnf_www 0 Sleep
当 iotop 看起来像这样：
Total DISK READ : 0.00 B/s | Total DISK WRITE : 1638.41 K/s
Actual DISK READ: 0.00 B/s | Actual DISK WRITE: 1852.28 K/s
TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND
4075 be/3 root 0.00 B/s 3.82 K/s 0.00 % 34.67 % [jbd2/sdc-8]
7745 be/4 mysql 0.00 B/s 1497.10 K/s 0.00 % 3.73 % mysqld
7747 be/4 mysql 0.00 B/s 30.55 K/s 0.00 % 2.34 % mysqld
7748 be/4 mysql 0.00 B/s 45.83 K/s 0.00 % 1.92 % mysqld
7741 be/4 mysql 0.00 B/s 0.00 B/s 0.00 % 1.64 % mysqld
7746 be/4 mysql 0.00 B/s 30.55 K/s 0.00 % 0.21 % mysqld
7742 be/4 mysql 0.00 B/s 0.00 B/s 0.00 % 0.08 % mysqld
14410 be/4 mysql 0.00 B/s 15.28 K/s 0.00 % 0.00 % mysqld
我总是看到几个进程不断地进行磁盘写入。我最近确实增加了 innodb_buffer_pool_size，以下是完整的设置，innodb_ 变量之后的所有设置都是我在运行 mysqltuner 后尝试过的，但没有得到真正的帮助：
[mysqld]
datadir=/db/mysql
tmpdir=/dev/shm
socket=/var/lib/mysql/mysql.sock
max_connections=125
symbolic-links=0
max_allowed_packet=512M
innodb_file_per_table
innodb_flush_method=O_DIRECT
innodb_buffer_pool_size=6G
innodb_log_file_size=1500M
innodb_buffer_pool_instances=6
query_cache_size=16M
query_cache_type=1
thread_cache_size=4
join_buffer_size=16M
tmp_table_size=256M
max_heap_table_size=256M
InnoDB 清除过程是否可能导致磁盘写入量如此之高？这是一个 WordPress 网站，我一直在查看慢速查询日志，这里有几个，但与看到的高负载没有任何关联。
大多数情况下，top 的样子是这样的：
top - 12:16:43 up 13:02, 3 users, load average: 5.32, 4.26, 4.25
Tasks: 202 total, 6 running, 131 sleeping, 0 stopped, 0 zombie
%Cpu(s): 15.5 us, 5.7 sy, 0.0 ni, 38.3 id, 1.2 wa, 0.0 hi, 0.5 si, 38.8 st
KiB Mem : 16419324 total, 289672 free, 4549808 used, 11579844 buff/cache
KiB Swap: 524284 total, 524284 free, 0 used. 11506900 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7731 mysql 20 0 10.1g 2.7g 20896 S 28.8 17.2 29:29.86 mysqld
15121 wmnf_ad+ 20 0 724508 107340 81852 S 27.2 0.7 0:01.83 httpd
15085 wmnf_ad+ 20 0 652008 115456 79932 R 22.2 0.7 0:01.90 httpd
15119 wmnf_ad+ 20 0 733080 111168 78336 S 11.9 0.7 0:02.73 httpd
14776 wmnf_ad+ 20 0 733724 126108 91168 S 10.9 0.8 0:05.19 httpd
14985 wmnf_ad+ 20 0 736768 119092 83020 S 9.6 0.7 0:02.72 httpd
14993 wmnf_ad+ 20 0 733832 118872 83732 S 9.6 0.7 0:05.91 httpd
14744 wmnf_ad+ 20 0 735768 129408 92820 S 8.6 0.8 0:05.60 httpd
13914 wmnf_ad+ 20 0 739364 131340 92704 S 7.9 0.8 0:14.55 httpd
14948 wmnf_ad+ 20 0 732920 110984 77456 R 6.3 0.7 0:03.08 httpd
我确实看到 innodb 正在写入这些 ibd 文件，而进程列表中没有任何内容，以下是 SHOW ENGINE INNODB STATUS 显示的内容：
=====================================
2018-05-29 12:40:26 0x7ff100325700 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 7 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 5814 srv_active, 0 srv_shutdown, 527 srv_idle
srv_master_thread log flush and writes: 6338
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 1030737
OS WAIT ARRAY INFO: signal count 588517
RW-shared spins 0, rounds 70740, OS waits 33434
RW-excl spins 0, rounds 94359, OS waits 4228
RW-sx spins 2111, rounds 55933, OS waits 1523
Spin rounds per wait: 70740.00 RW-shared, 94359.00 RW-excl, 26.50 RW-sx
------------
TRANSACTIONS
------------
Trx id counter 1213126
Purge done for trx's n:o < 1213126 undo n:o < 0 state: running but idle
History list length 3
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 422148390082168, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 422148390081352, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 state: waiting for completed aio requests (log thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: waiting for completed aio requests (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)
I/O thread 9 state: waiting for completed aio requests (write thread)
Pending normal aio reads: [0, 0, 0, 0] , aio writes: [0, 0, 0, 0] ,
ibuf aio reads:, log i/o's:, sync i/o's:
Pending flushes (fsync) log: 0; buffer pool: 0
124952 OS file reads, 245278 OS file writes, 82495 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 24.28 writes/s, 8.28 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 63, seg size 65, 70 merges
merged operations:
insert 37, delete mark 607, delete 0
discarded operations:
insert 0, delete mark 0, delete 0
Hash table size 1593833, node heap has 1953 buffer(s)
Hash table size 1593833, node heap has 178 buffer(s)
Hash table size 1593833, node heap has 97 buffer(s)
Hash table size 1593833, node heap has 2315 buffer(s)
Hash table size 1593833, node heap has 128 buffer(s)
Hash table size 1593833, node heap has 135 buffer(s)
Hash table size 1593833, node heap has 35 buffer(s)
Hash table size 1593833, node heap has 39 buffer(s)
765.60 hash searches/s, 525.21 non-hash searches/s
---
LOG
---
Log sequence number 12869849455
Log flushed up to 12869849455
Pages flushed up to 12869849455
Last checkpoint at 12869849331
0 pending log flushes, 0 pending chkp writes
53483 log i/o's done, 3.71 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total large memory allocated 6627000320
Dictionary memory allocated 3675472
Buffer pool size 393216
Free buffers 262869
Database pages 125467
Old database pages 46429
Modified db pages 0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 24, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 124488, created 979, written 162905
0.00 reads/s, 0.00 creates/s, 18.28 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 125467, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
----------------------
INDIVIDUAL BUFFER POOL INFO
----------------------
---BUFFER POOL 0
Buffer pool size 65536
Free buffers 43142
Database pages 21580
Old database pages 7985
Modified db pages 0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 1, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 21405, created 175, written 28103
0.00 reads/s, 0.00 creates/s, 5.57 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 21580, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 1
Buffer pool size 65536
Free buffers 43698
Database pages 21029
Old database pages 7782
Modified db pages 0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 1, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 20714, created 315, written 20255
0.00 reads/s, 0.00 creates/s, 6.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 21029, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 2
Buffer pool size 65536
Free buffers 43979
Database pages 20742
Old database pages 7676
Modified db pages 0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 10, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 20617, created 125, written 35035
0.00 reads/s, 0.00 creates/s, 4.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 20742, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 3
Buffer pool size 65536
Free buffers 43611
Database pages 21117
Old database pages 7815
Modified db pages 0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 4, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 20991, created 126, written 30631
0.00 reads/s, 0.00 creates/s, 1.71 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 21117, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 4
Buffer pool size 65536
Free buffers 44135
Database pages 20585
Old database pages 7618
Modified db pages 0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 1, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 20469, created 116, written 30474
0.00 reads/s, 0.00 creates/s, 0.71 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 20585, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 5
Buffer pool size 65536
Free buffers 44304
Database pages 20414
Old database pages 7553
Modified db pages 0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 7, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 20292, created 122, written 18407
0.00 reads/s, 0.00 creates/s, 0.29 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 20414, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
--------------
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
0 read views open inside InnoDB
Process ID=7731, Main thread ID=140666264016640, state: sleeping
Number of rows inserted 8611, updated 31931, deleted 19012, read 210937170
0.43 inserts/s, 1.86 updates/s, 0.00 deletes/s, 2021.00 reads/s
Number of system rows inserted 0, updated 0, deleted 0, read 0
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================
答案1
如果top您包含的输出是典型的，那么您的问题与 MySQL 无关。
%Cpu(s): 15.5 us, 5.7 sy, 0.0 ni, 38.3 id, 1.2 wa, 0.0 hi, 0.5 si, 38.8 st
^^^^^^^
注意到我最后强调的部分了吗？“st”代表“偷时间“。38.8% 的 CPU 时间是不可用由于主机上运行着其他虚拟机或进程。
如果您的虚拟机位于公共云中，请联系您的托管服务提供商，如果问题仍然存在，请考虑转移到另一台主机。
如果您的虚拟机托管在现场，则说明您的 VM 主机已超额订阅。请添加更多物理主机，或减少其他虚拟机的 CPU 负载。
答案2
根据问题中的初步信息，针对 my.cnf-ini [mysqld] 部分提出建议。
thread_cache_size=100 # from 4 to avoid strangling server with 234 qps
query_cache_min_res_unit=512 # from default to cache more results
innodb_lru_scan_depth=100 # from 1024 to minimize CPU busy every second
#join_buffer_size=16M # lead with # for default for this per connection RAM request
如需更多帮助，请参阅我的个人资料以获取联系信息。
当时间允许时，请让我们了解您的进展。